Problem: $ { \left[\begin{array}{rrr}{1} & {3} & {1} \\ {2} & {1} & {3}\end{array}\right]+\left[\begin{array}{rrr}{4} & {-2} & {0} \\ {-1} & {3} & {4}\end{array}\right] = {?} } $
Solution: To find the sum of two matrices, add the corresponding items between each matrix. ${\left[\begin{array}{rrr}{1}+{4} & {3}+{-2} & {1}+{0} \\ {2}+{-1} & {1}+{3} & {3}+{4}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rrr}{5} & {1} & {1} \\ {1} & {4} & {7}\end{array}\right]}$